We describe the structural and magnetic properties of a tetranuclear [2 × 2] Co4 grid complex containing a ditopic arylazo ligand. At low temperatures and in solution the complex is comprised of Co3+ and singly reduced trianion-radical ligands. In the solid state we demonstrate the presence of valence tautomerization via variable temperature magnetic susceptibility experiments and powder-pattern EPR spectroscopy. Valence tautomerism in polynuclear complexes is very rare and to our knowledge is unprecedented in [2 × 2] grid complexes.
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http://dx.doi.org/10.1039/d1cc01991k | DOI Listing |
Angew Chem Int Ed Engl
December 2024
Universität Heidelberg: Universitat Heidelberg, Anorganisch-Chemisches Institut, Im Neuenheimer Feld 270, 69120, Heidelberg, GERMANY.
Electromerism (aka. valence tautomerism) corresponds to the switching of electronic distributions between redox-active ligands and central elements. While this phenomenon is well established for several transition metals, the Pd(0)/Pd(II) couple could not yet be involved due to the high energy of the Pd(0) state.
View Article and Find Full Text PDFChem Commun (Camb)
December 2024
Department of Chemistry, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
Coordination networks based on lanthanide ions entangle collective magnetic phenomena, otherwise only observed in inorganic 4f materials, and the tunable spatial and electronic structure engineering intrinsic to coordination chemistry. In this review, we discuss the use of 2D-structure-directing linear {LnI} nodes to direct the formation of polymeric coordination networks. The equatorial coordination plasticity of {LnI} results in broad structural diversity, including previously unobtainable tessellations containing motifs observed in quasicrystalline tilings.
View Article and Find Full Text PDFDalton Trans
November 2024
International Tomography Center of the SB of RAS, Institutskaya Str, 3a, Novosibirsk 630090, Russia.
Expression of concern for 'Valence tautomeric interconversion of bis-dioxolene cobalt complex with imino-pyridine functionalized by TEMPO moiety in solid solutions with isostructural nickel analogue: phase transitions and monocrystal destruction' by Michael P. Bubnov , , 2024, , 9151-9160, https://doi.org/10.
View Article and Find Full Text PDFJ Org Chem
November 2024
Laboratory of Advanced Computation and Theory for Materials and Chemistry, Department of Chemistry, National Institute of Technology Warangal (NITW), Warangal, Telangana 506004, India.
The thermal electrocyclic ring opening of fused -cyclobutene to ,-diene is prohibited according to the Woodward-Hoffmann (WH) rules; nonetheless, experiments provide firm evidence for their formation. However, the mechanism, electronic structure, and behavior during the reaction are ambiguous. Herein, we attempt to gain insights into the mechanism of thermal ring opening in four -heterocycles containing a conjugated diene as the core skeleton.
View Article and Find Full Text PDFNat Commun
October 2024
School of Molecular Sciences, University of Western Australia, Crowley, Western Australia, Australia.
Molecules that can reversibly switch between electronic states under an external stimulus are of interest to numerous applications. Complexes of open shell metal ions with redox active ligands undergo valence tautomerism, resulting in magnetic, colour and structural switching, relevant to data storage and actuators. However, the precise structural changes occurring during valence tautomerism in the solid state are unclear due to the lack of atomic-resolution characterization.
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